BrlR from Pseudomonas aeruginosa is a c-di-GMP-responsive transcription factor.
BrlR from Pseudomonas aeruginosa is a c-di-GMP-responsive transcription factor.
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DOI：
10.1111/mmi.12562
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发表时间：
2014-05
影响因子：
3.6
通讯作者：
Sauer K
中科院分区：
文献类型：
--
作者：
Chambers JR;Liao J;Schurr MJ;Sauer K
转录调控因子BrlR是多药转运激活剂MERR家族的成员，与铜绿假单胞菌生物被膜的高度耐药有关。虽然已知MerR调节剂在诱导剂结合时既能激活多药外排泵基因的表达，又能激活它们自己的转录，但对BrlR的激活知之甚少。我们使用启动子报告菌株，体内和体外DNA结合分析结合5‘RACE，证明BrlR与自己的启动子结合，很可能是通过类似Merr的回文序列。与已知的MerR多药转运激活剂不同，BrlR和brlR的表达不受多药转运底物的激活。相反，二级信使c-di-GMP增强了BrlR-DNA的结合。除了BrlR-DNA结合增强外，c-di-GMP水平还有助于初始附着细胞中PbrlR启动子的活性，c-di-GMP水平升高与brlR表达增加相关。虽然BrlR不含有类似于先前定义的c-di-GMP结合域的氨基酸基序，但在体外发现，BrlR以一个c-di-GMP与两个BrlR的比例结合c-di-GMP。交联分析证实，在c-di-GMP水平升高的情况下，二聚体的形成会增强。我们的发现表明BrlR是一个不寻常的Merr家族成员，因为BrlR的功能和表达需要二级信使c-di-GMP。
The transcriptional regulator BrlR is a member of the MerR family of multidrug transport activators that contributes to the high-level drug tolerance of Pseudomonas aeruginosa biofilms. While MerR regulators are known to activate both the expression of multidrug efflux pump genes and their own transcription upon inducer-binding, little is known about BrlR activation. We demonstrate using promoter reporter strains, in vivo and in vitro DNA-binding assays combined with 5’RACE, that BrlR binds to its own promoter, likely via a MerR-like palindromic sequence. Unlike known MerR multidrug transport activators, BrlR and brlR expression are not activated by multidrug transporter substrates. Instead, BrlR-DNA binding was enhanced by the secondary messenger c-di-GMP. In addition to enhanced BrlR-DNA binding, c-di-GMP levels contributed to PbrlR promoter activity in initial attached cells with elevated c-di-GMP levels correlating with increased expression of brlR. While not harboring amino acid motifs resembling previously defined c-di-GMP-binding domains, BrlR was found to bind c-di-GMP in vitro at a ratio of one c-di-GMP per two BrlR. Crosslinking assays confirmed dimer formation to be enhanced in the presence of elevated c-di-GMP levels. Our findings demonstrate BrlR to be an unusual MerR-family member in that BrlR function and expression require the secondary messenger c-di-GMP.
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影响因子：
5.8
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通讯作者：
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